Earthquake Warning for the Cascadia Subduction Zone Past!
Next chance follows the Episodic Tremor and Slip - Earthquakes
Here on the West Coast of Canada we have what's called an Episodic Tremor & Slip (ETS) that occurs on a fairly regular cycle every 14 months and lasts for 2 weeks. This is caused by the Juan De Fuca Plate Subducting under the North American Plate at a rate of roughly 2-5 cm (0.98 Inches)/year which pushes our mountains up approximately 3 mm (0.11811 inches) per year. However the Northern part of the Subduction Fault is locked and every ETS adds more pressure to the locked area. When this slips the North American Plate could move up to 10 to 20 Meters Seawards. Causing a Mega Thrust Earthquake of 9 or higher Magnitude. Due to the Periodicity of the Cycle of the ETS, this could occur at any time.
Cascadia Subduction Zone:
The westerly boundary of the North American Plate is the Queen Charlotte Fault running offshore along the coast of Alaska and the Cascadia subduction zone to the north, the San Andreas Fault through California, the East Pacific Rise in the Gulf of California, and the Middle America Trench to the south. West of Vancouver Island, and extending from the north tip of the Vancouver Island to northern California, the oceanic Juan de Fuca plate is moving towards North America at about 2-5 cm (0.98 Inches)/year. This region is called the Cascadia subduction zone. Here, the much smaller Juan de Fuca plate is sliding (subducting) beneath the North America continent. It is about 45 km (27.96 Miles) beneath Victoria, and about 70 km (43.50 Miles) beneath Vancouver. The ocean plate is not always moving though.
There is good evidence that the Juan de Fuca and North America plates are currently locked together, causing strain to build up in the earth's crust. It is this squeezing of the crust that causes the 300 or so small earthquakes that are located in southwestern British Columbia each year, and the less-frequent (once per decade, on average, damaging crustal earthquakes (e.g., a magnitude 7.3 earthquake on central Vancouver Island in 1946). At some time in the future, these plates will snap loose, generating a huge offshore "subduction" earthquake - one similar to the 1964 M=9.2 Alaska earthquake [http://en.wikipedia.org/wiki/1964_Alaska_earthquake], or the 1960 M=9.5 Valdivia, Chile earthquake [http://en.wikipedia.org/wiki/1960_Valdivia_earthquake]. Current crustal deformation measurements in this area provide evidence for this model. Geological evidence also indicates that huge subduction earthquakes have struck this coast every 300-800 years.
This last occurred on December 26, 1700 at 9:00pm. Will it happen this Year?
Natural Resources Canada
Global News Canada -- Original
List of 20th-century earthquakes